Hydroelectric dams are a good source of renewable energy and also carry the potential of positively impacting the environment, though they sometimes have the opposite effect. As long as the dam is placed correctly and engineered carefully, the overall contribution to society is positive. As long as not too many are constructed, they are very worth it.
Considering the present environmentally devastating course the use of fossil fuels has placed upon the ecological balance of the earth, some harsh decisions may have to be made. In light of the nearly non-existent external harms that hydroelectric energy causes once it is in place an operational, this source of energy must be further researched with a constant eye on improving the aspects that are detrimental to the ecosystems. Hydroelectric dams have proven to be one of the most cost effective mechanism to generate energy and therefore in light of the even more destructive nature of alternative energy sources should be pursued with a goal of improving the design to be even more environmentally friendly.